The correct option is A 5H2CO2+2KMnO4→5CO2+K2O+2MnO+5H2O
The unbalanced redox equation is as follows:
H2CO2+KMnO4→CO2+K2O+MnO
Balance all atoms other than H and O.
H2CO2+2KMnO4→CO2+K2O+2MnO
The oxidation number of Mn changes from +7 to 2. The change in the oxidation number of Mn is 5. Total change for 2 Mn aoms is 10.
The oxidation number of C changes from +2 to +4. The change in the oxidation number is 2.
The increase in the oxidation number is balanced with decrease in the oxidation number by multiplying H2CO2 and CO2 with 5.
5H2CO2+2KMnO4→5CO2+K2O+2MnO
O atoms are balanced by adding 5 water molecules on RHS.
5H2CO2+2KMnO4→5CO2+K2O+2MnO+5H2O
This is the balanced chemical equation.